Field Experimental Investigation on Human Thermal Comfort in Vehicle Cabin

A comfortable thermal environment can alleviate fatigue, reduce irritability, and improve driving safety. However, it is rather a challenge to evaluate thermal comfort inside a vehicle due to multifarious geometric and environmental factors as well as human differences. This study conducted a series of field experiments both in summer and winter conditions, measuring the thermal environment parameters inside the compartment and the skin temperature of experimental personnel, and carrying out subjective thermal sensation and comfort questionnaires. The experimental results showed that head and trunk are the most relevant parts of all human body parts to the overall thermal sensation/comfort. For overall thermal sensation, the value of regression R² referring to head/trunk is 0.691/0.721, while those corresponding to overall thermal comfort is 0.802/0.773. And the value of regression slopes of thermal sensation and thermal comfort are 0.893/0.846 and 0.938/0.946 for head and trunk, respectively. Meanwhile, it is also found that, when people are in a hot cabin thermal environment, the integrated effect of all body parts made the overall thermal sensation of passengers greater than the individual one of each part, and the overall thermal comfort is much more affected by the most uncomfortable part than the comfortable parts.